The language of the European Union’s Treaty of Lisbon, its last major constitutional document, is so insistently moral that one can almost lose sight of its practical details. “The Union,” it states, “is founded on the values of respect for human dignity, freedom, democracy, equality, the rule of law and respect for human rights, including the rights of persons belonging to minorities.” Its “aim is to promote peace” and “the well-being of its peoples.”

In the exhilaration that followed the collapse of the Soviet Union and the reunification of Europe, peace and well-being seemed no more, and no less, than the continent’s destiny. That euphoric end-of-history moment has, of course, turned out to be transitory, and the high-minded boilerplate of 1992 has become today’s burning ground. When voters go to the polls this May to choose a new European Parliament, an event that in the past has barely provoked a yawn, that larger idea–not the euro or the single market, and not the EU itself, but the post-Cold War conception of a federated space with harmonized policies on core issues and a joint commitment to democracy and the rule of law–will be at risk.

What has changed, of course, is the rise of nationalist parties, which now rule in Hungary, Poland, and Italy, and have grown in popularity in virtually every other major country in Europe. Current polls in France, for example, show French President Emmanuel Macron’s En Marche! (In Motion!) running no better than even with Marine Le Pen’s Rassemblement National (formerly the National Front). Italy’s Northern League party and Five Star Movement and Poland’s Law and Justice are also expected to make major gains–though so, too, are Green parties from Germany and Holland.

Mainstream parties are virtually certain to win many more seats than explicitly anti-European ones, but that’s not a very meaningful threshold. Even figures like Le Pen or Hungarian Prime Minister Viktor Orban no longer threaten to leave the EU. They have read the polls that show that two-thirds of European citizens think their country benefits from the EU–the highest figure ever. Instead they speak of a “Europe of sovereign nations”—a weak federation that would preserve the material benefits of the EU but minimize its role on foreign policy, human rights, the rule of law. That is the danger posed by the upcoming election.

Europe may have more internationalist than nationalist voters, but the nationalists have all the passion. It is they, and their leaders, who have sought to use the election to bury the liberal internationalist vision. Last year, Matteo Salvini, the charismatic leader of the Northern League, told a rally, “The European elections next year will be a referendum between the Europe of the elites, of banks, of finance, of immigration and precarious work; and the Europe of people and labor.” Steve Bannon, U.S. President Donald Trump’s former éminence grise, has sought to build a network of European populists, though so far he seems mostly to have learned how fractious the nationalist right is.

Who, on the other hand, speaks for Europe? Mostly the Eurocrats. Last September, eight prominent centrist politicians issued a call to “reinvent” Europe lest it be “suffocated” by forces that would turn back the clock to the national enmity and even the fascism of the 1930s. That barely caused a ripple. The European People’s Party, the center-right coalition that currently controls the plurality of the seats in the European Parliament, chose as its leader Manfred Weber, an uninspiring veteran from Germany’s Christian Social Union. Weber is likely to become the next president of the European Commission. Susi Dennison, an EU expert with the European Council on Foreign Relations, says that the nationalists “have done a better job of understanding the emotions that are driving European politics at the moment than the centrist parties have.”

Except for the irrepressible Macron, the one-man European crusade. Two years ago, Macron gave a very, very long speech at the Sorbonne proclaiming that it is in Europe where “our battle lies, our history, our identity, our horizon, what protects us and gives us a future.” Macron insisted that Europe needs more EU, not less, in order to confront transnational problems–a defense force, a European Public Prosecutor’s Office, a European border police force and so on. It was a magnificent speech but it landed with a thud, since Macron’s chief partner, Chancellor Angela Merkel of Germany, had already begun to retreat before growing anti-EU sentiment, and in any case regarded visionary projects with a gimlet eye.

Macron has returned to the lists. On March 4, he published in 28 newspapers (one for each EU member) a ringing call for a “European Renaissance.” As before, he passionately reaffirmed his faith in the idea of Europe, and as before called for many new EU institutions. The reception among EU leaders and fellow heads of state was warm but vague; neither Merkel nor any of her colleagues are eager to upset a status quo that already feels perilous. Macron seems to be the only leader in Europe prepared to go to the wall over Europe, or at least over the EU. And after six months of gilet jaune demonstrations and a general tarnishing of a once shiny reputation, Macron’s trumpet no longer rouses the public as it once did.

Yet Macron is plainly right on the merits. Though right-wing politicians in the United Kingdom persuaded voters in 2016 that Brussels lay at the root of all their problems, and though figures like Salvini and Orban have managed to make the EU feel as remote and inhuman as Kafka’s castle, it’s incontestable that Europe cannot deal with problems like immigration and the flow of refugees, the threat from Russia, cybersecurity, and privacy, unless it can act collectively. Nor can individual European nations compete economically on an equal footing with the great powers. And it is true as well that if the EU no longer enforces principles of human rights and the rule of law, as Viktor Orban foresees, then Europe will become a mere geographic designation rather than a living idea.

The problem for the internationalists is that the EU often does feel remote and inhuman. If hardly anyone cares about the European Parliament, that is in part because so much power lies instead with the unelected administrators of the European Commission. The predecessor institutions of the EU were designed in the postwar era not to be transparent and accountable, but to protect liberal principles from illiberal democratic majorities; the EU thus makes the perfect target for populist leaders. That is why even figures like Macron and Guy Verhofstadt, leader of an EU party coalition and the author of Europe’s Last Chance, recognize that the EU needs to be “reinvented.” Like the United Nations, however, the EU may prove to be unreinventable. Or it may be suffocated before it has a chance to reinvent itself.

Yet the institution cannot resist the larger political changes in Europe. Whether or not anti-EU parties are able to attract a third of the vote, which Dennison describes in a recent paper as the threshold for serious mischief, the major parties of the center-left and center-right, which have collapsed across Europe, are bound to do worse than they ever have before. Until now, these two loose groupings have kept a grip on power in the Parliament. Now they will have to forge new coalitions and empower new groups. Stefan Lehne and Heather Grabbe of Carnegie Europe have argued that while no reform has ever succeeded in increasing popular interest in the European Parliament, breaking the party logjam just might do it. “The EP legislative process might become less efficient,” he writes, “but the overall effect on EU-level democracy could be positive.”

That, however, is for tomorrow. The question for today–for May 23-26, to be exact–is whether the unprecedented stakes of this election will bring to the polls more people who want the EU to be reinvented, or more people who want it to be diminished. A great deal hangs on that.

Correction, March 18, 2019: The leader of Italy’s Northern League is Matteo Salvini. A previous version of this story misspelled his first name.

James Traub is a regular contributor to Foreign Policy, a fellow at the Center on International Cooperation, and author of the book "John Quincy Adams: Militant Spirit."